1. Field of the Invention
The present invention relates to a bag which is Suitable for use in an air bag apparatus activated upon action of a predetermined load and which is expanded toward the side of an occupant when the air bag apparatus is activated and to a method of manufacturing the bag.
2. Description of the Related Art
In an air bag apparatus of such a type that it is provided inside a vehicle door, for example, a bag is expanded toward the side of an occupant seated on his/her seat where a predetermined load is externally applied to the vehicle door. Thus, the occupant is protected from an impact produced when such a load is applied to the door.
Since a space defined between a trim of the vehicle door and an occupant's side is narrow, this type of air bag apparatus differs from an air bag apparatus or the like used for a driver's seat. Further, a large restriction is imposed on the shape of the bag, specifically its thickness. Therefore, the bag is shaped in the form of a thin rectangular parallelopiped.
When the predetermined load is externally applied to the vehicle door so as to expand the bag, the occupant is protected from the impact by abutting against the bag. Simultaneously, however, the pressure in the bag abruptly increases upon abutment of the occupant against the bag. It is thus necessary to improve the strength of the bag in order to ensure cushioning properties (energy absorption properties) of the bag.
When a plurality of reinforcing fabrics or the like are simply superimposed and sewn on a bag or when a number of reinforcing fabrics are provided inside the bag in order to improve the strength of the bag shaped in the form of the thin rectangular parallelopiped as described above, a lot of labor becomes cumbersome and the efficiency of work is reduced. Thus, the manufacturing cost is extremely high.